I find this problem really though. I did solve for it's derivative and then by EVT tried to find its crititcal points. I get (-π/2) and (π/2) for f'(x)=0.
The problm is that I'm not sure if there are more solutions for f'(x).

and -(cosx)^2 is a negative value for all values of x so you just have the value of x which make cosx zero like pie/2 + n pie n a natural number
the solution is pie /2 and -pie/2
there is no other solution

my answer is very long

May 19th 2009, 08:13 PM

Spec

You'll eventually end up with the equation which has the solution

May 20th 2009, 01:59 PM

Arturo_026

So how should I answer the question? since I'm not given any interval and there are infinately many solutions.